

package com.hazelcast.jet.impl.pipeline.transform;

import com.hazelcast.function.FunctionEx;
import com.hazelcast.function.ToLongFunctionEx;

import javax.annotation.Nonnull;
import java.util.function.Supplier;

import static java.lang.Math.max;

abstract class StatefulKeyedTransformBase<T, K, S> extends AbstractTransform {

    private static final int TTL_TO_WM_STRIDE_RATIO = 10;

    final long ttl;
    final FunctionEx<? super T, ? extends K> keyFn;
    final ToLongFunctionEx<? super T> timestampFn;
    final Supplier<? extends S> createFn;

    StatefulKeyedTransformBase(@Nonnull String name, @Nonnull Transform upstream, long ttl, @Nonnull FunctionEx<? super T, ? extends K> keyFn, @Nonnull ToLongFunctionEx<? super T> timestampFn, @Nonnull Supplier<? extends S> createFn) {
        super(name, upstream);
        this.ttl = ttl;
        this.keyFn = keyFn;
        this.timestampFn = timestampFn;
        this.createFn = createFn;
    }

    @Override
    public final long preferredWatermarkStride() {
        return max(1, ttl / TTL_TO_WM_STRIDE_RATIO);
    }
}
